Hydraulic press



HYDRAULI C PRESS Filed Aug. 3l. 1929 2 Sheets-Sheet i l Tnvcmor,

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J H. F. Maaik/@LUN HYDRAULIC FRESS O K 4 Filed Aug. 5l, 1929 2 Shees-Sheet 2 ,gg/7 F f: if 7%- l 75 Yi .9# n

nii? a Patented ct.. 25', 1932 UNITED STATES PATENT OFFICE HOWARD F. MACMILLIN, OF MOUNT GILEAD, OHIO, ASSIGNOR '10 HYDRAULIC PRESS MANUFACTURING COMPANY, OF MOUNT GILEAD, OHIO HYDRAULIC PRESS Application led August 31, 19.29. Serial No. 389,761.

My invention relates to hydraulic presses and more particularly to improvements in valve mechanism for controlling the operation of such presses.

In the co-pending applications of Walter Ernst, Serial No. 296,129, filed July 30, 1928, and Serial No. 334,746, filed J an. 24, 1929, are shown hydraulic presses which are provided with means for advancing the reciprocatory platen of the press rapidly during the initial part of the pressing stroke as compared to the latter part thereof, these means including valves adapted to place the main pressingr cylinder of the press in substantially open communication with a source of fluid supply under static pressure such as a surge tank during the initial part of the pressing stroke, and to subsequently place the pressing cylinder in communication with a source of high pressure fluid such Ias a pump or the like during the latter part of the pressing stroke. The first part of the pressing stroke is accomplished by lie application of pressure to auxiliary or booster cylinders.

In other presses of generally similar construction the first part of the pressing stroke .is accomplished under the influence of the weight of the platen assisted by the static head in the surge tank.

In both types of press it is necessary that high pressure fluid be admitted to the main ypressing cylinder when the platen encounters resistance to its downward travel. This is usually accomplished by closing communication between the pressin cylinder and the surge tank and by opening communication between the pressing cylinder and a high pressure pump when the platen meets the work.l The platen is then returned to its starting position by means of a ram or piston mounted in a platen returning cylinder, which may be of either the pull back or the push back variety.

Hydraulic presses having the aforenamed operating characteristics and which have been heretofore constructed have been provided with at least two separate valves for controlling admission of fluid under pump pressure to the main cylinder and tothe platen returning cylinder for effecting reciprocations of the platen and for controlling communication of the surge tank with the main pressing cylinder for effecting the rapid prcfilling of the pressing cylinder during the initial part of the pressing stroke of the platen. Because of the fact that the pump pressure employed in operating such presses is quite high, usually being several thousand pounds per square inch, thel valves for controlling the various application of pressure are necessarily heavy and consequently eX- pensive, and are also, because of the high pressure of the fluid which they control, susceptible to a certain amount of leakage. For

these reasons it is desirable that the valves controlling the application of high pressure fluid in a hydraulic press be of as simple construction as possible and also be so arranged tha: theymay be located within the surge tan t.

An object of my invention is to provide a single control valve of simplified construction for controlling the application of high pressure to the pressing and platen returning cylinders of a hydraulic press and which is adapted to afford relatively open communication between the surge tank and the pressing .(-ylinden Another object of my invention is to provide means associated with a control valve of the character described for actuating the latter in a manner to produce complete automatic operation of the press in which the platen automatically performs an indeterminate number of pressing operations, and which is also adapted to actuate the valve in a manner to effect semiautomatic operation of the press, in which the platen .is operated under manual control to automatically perform a complete pressing and a complete f return stroke, at the end of which it will come to rest in its uppermost position.

Further objects of my invention will become apparent from a rea dingof the following description, the appended claims, and the several views illustrated in the drawings, in which:

Figure 1 is a front elevation of a hydraulic press and associated press operating hydraulic circuits embodying my invention,

parts of the press and certain valves being shown in section, the valves being shown in the osition which they will occupy during the iii-st part of a pressingstroke of the platen.

Figure 2 is a view showing in section and on an enlarged scale certain of the valves in the positions which they will occup during the latter part of the pressing) stro e of the platen, the connecting piping eing removed in art for better utilization of space.

igure 3 is a view similar to Figure 2 but showing the positions the valves will occupy during a return stroke of the platen.

Fi re 4 is a view similar to Figure 2 but showing the positions the valves will occupy when the platen is at rest in its uppermost position, and t Figure 5 is a fragmentary or detail view of aid operating rod and a lug for guiding the r My invention may be embodied in various types of hydraulic presses, but, in the present instance, is illustrated in connection with a press A of the downward pressure type including a base 1, a press head 2 connected to the base by strain rods 3, and a reciprocatory platen 4 mounted for vertical sliding movement on the strain rods. For eiiecting reciprocatory movements of the platen, I provide hydraulic platen actuating means comprising a pressing cylinder 5 lcarried by the press head, a ram 6 reciprocable in the pressing cylinder, two push back or platen returning cylinders 7, 7 each having a high pressure end 8 and a low pressure end 9, and pistons 10 slidably mounted inthe push back cylinders and each connected to the platen 4 by a piston rod 11. y

The pressing cylinder 5 and the high pressure ends of the platen returning cyilnders are part of a high pressure hydraulic circuit, and valve means are providedin this circuit for directin fluid under pressureA to the respective cylinders for effecting either automatic or semiautomatic operation of' the press.

The high pressure hydraulic circuit includes a hlgh pressure pump B which may be of conventional form and which is provided with, an intake pipe line 12 connected to a surge tank 13, and with a discharge pipe line 14 connected to a control valve C which is preferably located in the surge tank and mounted o the upper end of the pressing cylinder 5. A by-pass valve Dis interposed between portions 15 and 16 of the pipeline 14l and normally provides direct communication between the control valve and the pump.

The control valve C includes a valve casing 17 formed with a valve chamber 18 which extends through the casing and which is closed at its opposite ends by hollow heads 19 and 20 respectively. A piston valve 21 is mounted for sliding movement within the casing 17 and comprises spaced heads 22,

23, and 24 respectively, a stem 25 disposed between and connecting the heads 22 and 23, and a stem 26 disposed between and connecting the heads 23 and 24.

The casing 17 is provided with ports 27 and 28 respectively locatedadjacent opposite ends of the casing and adapted to alford relatively open communication between the surge tank 13 and the valve chamber 18. An `opening 29 formed in a plug 30, removably mounted in the casing 17 intermediate the port 27 and the center of the casing, provides relatively restricted communication between the valve chamber and the surge tank; and a port 31 formed in the valve casing intermediate the opening 29 and the ports .28. provides direct communication between the valve chamber and an opening 32 in the pressing cylinder. s

The pipe line 14 is, adapted to communicate with thel valve chamber 18 by means of a port 33 in the valve casing, and a pipeline 34 communicates at one of its endslwith the high pressure ends 8 of the push back cylinders 7 and its other end is adapted to communicate with the 'valve chamber 18 by means of a port 35.

When the piston valve 21 is in the posi-'- tion shown in Figure 1, it is desirable that the pipe line 14 communicate with the surge tank. For providing this communication,

the piston valve is formed with a longitudinal passage 36 extending inwardly through the head 22 and the stem 25 andcommunicating at its inner end with a lateral passage 37 which extends from the longitudinal passage outwardly through thehead 23 and communicates with an annular recess 38 formed in the head 23.

I The valve C controls the application of pressure tothe platen actuating means for effecting reciprocations of the laten, and in controlling this application .o pressure the piston valve 21 is movable to three distinct positions, the first of which is illustrated in Figure 1, this position being that which the valve occupies when the platen is starting a pressing stroke. When the valve is in the Figure 1 position the pressing cylinder 5 is in .relatively open communication with the surge tank by means of the o ening 32 in the cylinder, the port 31 in the valve, the

valve chamber 18, and the ports 28, and

simultaneously the high pressure end of the push back cylinders has rrelatively restricted communication with the surge tank by means of the pipe line 34, thev ort 35, and the small opening 29. This re atively restricted.

communication between the push back cylinders and the surge tank retards the descent of the platen, and by usin plu s having different sized openings in p ace o the plug 30, any desired rate of descent of the platen may be obtained. When the valve is in this position, the platen will coast downwardly under the influence of its own weight assisted by the slight pressure on the ram 6 which is due to the static head of the fluid in the surge tank. During this gravitational descent of the platen the discharge of the high pressure pump will pass through the pipe line 14, the passages 36 and 37 in the piston valve, and thence out through the opening 27 and into the 'surge tank.

When the platen encounters resistance to its downward travel during its pressing stroke, the piston valve 21 will be moved from its first or Figure 1 position to its second position as shown in Figure 2 in a manner to be hereinafter described. Vhen the valve is in this second position, the head 24 of the valve is positioned between the ports 28 and the port 31 thereby closingcommunication between the surge tank and the pressing cylinder, and the head 23 is positioned to the left of the port 33 so that fiuid under pressure from the pump B will be directed intothe pressing cylinder by means of the lpipe line 14, the valve chamber 18, the port 31 in the valve casing, and the opening 32 in the cylinder. The high pressure ends of. the push back cylinders will still communicate with the s urge tank by means of the pipe line 34, the port 35, the Valve chamber 18, and the opening 29. The high pressure fiud directed to the pressing cylinder will then move the platen downwardly to complete its pressing stroke.

lVhen the platen has completed its pressing stroke, means responsive to the pressure in the main cylinder, and which will be hereinafter described in detail, move the piston valve 21 to the Figure 3 position. In this position of the valve the main press cylinder communicates with the surge tank by means of the opening 32 in the cylinder, the port 31 in the valve casing, the valve chamber 18, and the ports 28. At the same time the discharge `rom the high pressure pump will be directed to the high pressure end of each of the push back cylinders by means of the pipe line 14, the port 33, the valve chamber 18, the port 35, and the pipe line-34, and the platen will. then perform a return stroke.

From the foregoing it will be observed that the piston valve 21 of' the control valve is movable to three positions for effecting a complete reciprocation of the platen. When in the first or Figure 1 position, the valve simultaneously affords relatively open communication between the surge tank and the pump, and between the surge tank and the pressing cylinders: and relatively restricted communication between the surge tank and the platen returning cylinders for effecting a gravitational descent of the platen. ll'hen in the second or Figure 2 position, the valve affords communication between the pump and the pressing cylinder and also between the surge tank an-d the platen returning cyl- 'cated outside of the surge tank, to effect movements of the piston valve 21 to each of the three positions described above. For accomplishing this purpose, I provide pressure responsive means adapted to cooperate with the piston valve and mounted in the hollow heads 19 and 20. This pressure responsive means includes a plunger 39 mounted for sliding movements in-a bore 40 in the head 19 and extending into a pressure chamber 41 in the head and into the valve chamber 18.

The head 19 is provided with anropening 42 through which fiuid under pressure is admitted to the chamber 41 in a manner to be later described, and the Afiuid under pressure .thus admitted acts upon the plunger 39 to move the latter to the right as viewed in the drawings. Thus when the piston valve 21 of 9B the control valve is in thc Figure position and fluid under pressure 1s admitted -to the pressure chamber 41, the plunger 3,9 will be moved to the right and will engage the head 22 of the piston valve -and move the latter` to 100 its extreme right hand position as shown in Figures 3 and 4. y

For moving the piston valve 21 to the left, the head 20 is provided with alined pressure chambersv 43 and 44 which are separatedby a partition 45. A plunger 46 is slidably mounted in the chamber 43, and is adapted when moved to the left to engage the head 24 of the piston valve and to thereby move the latter' to the left. A plunger 47 is mounted for sliding movements in a bore 48 in the partition and extends into the chambers 43 and 44, the end of the plunger which extends into the chamber 44 being provided with an enlarged head 49 adapted to engage the partition 45 to limit the movement of the plunger to the left. Openings 50 and 51 provide inlets for introducing fluid under pressure to the chambers 43 and 44 respectively.

lV hen the piston valve 21 is in its extreme righthand position as shown in Figures 3 and 4, and pressure is admitted to the chamber 44, the plunger 4T will be moved to the left and will engage the plunger 46, thereby moving' it to the left, and the plunger 46 will engage the piston valve, moving it to the le tt' until the enlarged head 49 engages the partition 45 and arrests movement of the plunger 47 when the valve 21 has reached the Figure 1 position.

When fluid under pressure is admitted to the chamber 43, the plunger 46 will be moved farther to theleft and will thus move the piston valve to its extreme left hand position as shown in Figure 2.

The by-pass valve D which is interposed in the pump discharge line 14 between the control valve and the pump serves to bypass the discharge of the pump to the surge .tank when the platen approaches the end of a return stroke during semiautomatic operation of the press to thereby allow the platen to dwell in its uppermost position. It is to be understood that, when the press is operated under full automatic control, in which the lplaten starts a pressing stroke immedi-l ately upon the completion of a return stroke instead of coming to a state of rest at the end of the return stroke, the by-pass valve merely forms a part of the discharge line 14. However, when it is desired that the platen come to a rest .at the end of a return stroke, the discharge from the pump is diverted from the control valve C and by-passed back to the tank. The by-pass valve includes a valve casing 52 formed with a' valve chamber 53 and a piston valve 54 slidably mounted therein, the piston valve being provided with spaced heads 55 and 56 andvvith a projection 57 on the head 56 which is adapted to engage the right hand end of the valve casing for limiting the movement of the piston valvew to the right. An opening 58 formed in the valve casing affords communication between the valve chamber 53 and the pipe 15, a port 59 formed in the valve casing is ada ted to afford communication between the val)ve chamber and the pipe 16, and a port 60 in the valve casing is adapted to afford communication between the valve chamber and the surge tank.

The piston valve 54 is arranged to be moved either to the right or to the left by the application of fluid under pressure, the valve f2 being moved to the right when fluid is admitted tothe valve chamber' through an opening 61 in one end of the casing and is moved to the left `when pressure fluid is admitted to the chamber through an opening 62 at the opposite end thereof. vWhen the piston valve 54 is in the position shown in Figures 1, 2, and 3, the port 60 will be covered by the head 55 of the piston valve and the pump B will communicate with the control valve C by means of the pipe 15, the opening` 58 in the valve casing 52, the valve chamber 53, the opening 59, andthe pipe 16. When the piston 'valve is moved to the left, l that is, to the'position shown in'y Figure 4, the head 56 will cover the port 59 so as to trap -llu'id in the pipe 34 and the high pressure end of each of the platen returning cylinders to thereby maintain the platen at rest in itsuppermost position, and the discharge pipe 15 will communicate with the surge tank by means of the opening 58 the valve chamber 53, and the port 60, so that the discharge of the pum will be diverted from the vcontrol valve and'will be by-passed into the surge tank.

For applying fluid pressure to the pressure responsive valve actuating means associated with valves C and D, I provide a low pressure hydraulic circuit in accordance with the present invention which includes means controlling the application of low pressure fluid to the pressure chambers 41, 43, 44, and to the opposite ends of the valve casing 52 of the valve D. Low pressure pilot circuits for operating main control valves are shown, described, and claimed in the copending application of Walter Ernst, Serial No. 37 3,- 985, filed June 27, 1929, and in the patent to Ernst, No. 1,763,142, issued June 10, 1930. The low pressure circuit includes a low pressure pump Efwhich receives Huid from a tank 63 through a suction pipe 64 and discharges ,fluid under pressure through a pipe line 65, a pressure actuated relief valve 66 of conventional design being interposed in a branch pipe 67 which connects the pipe 65 with the tank 63. The relief valve 66 definitely limits the maximum pressure attained in the low pressure circuit and serves to by-pass fluid from the pump E to the tank 63 when pressure builds up in the low pressure circuit.

Thelow pressure discharge line is connected to a main pilot valve F which includes a casing 67 a and a chamber 68 formed therein. The pipe 65 communicates at all times with the chamber by means of an opening 69 in the casing, and a piston valve 70 having spacedheads 71 and 72 is mounted for sliding movements within the casing for controlling the application of low pressure fluid delivered by the pump E. The chamber`68 is in constant communication at its opposite ends with the tank 63 b means of a return pipe line 73 which has branches 74 and 75 connected to the casing at the opposite ends thereof. A pipe 76 connected to the casing is adapted to communicate at one of its ends with the valve chamber by means of a port 77 and communicates at its other end' with the chamber 41 in the head 19 of the control 115.

valve C. A pipe 78 is adapted to communicate at one of its ends with the valve chamber by means of a port 79 in the valve, casing, and communicates' at its other end with the chamber 44 in the head 20 of the control 120 valve.

.When the piston valve 70 is in the position shown in Figures 1 and 2, the discharge from the low pressure pump will be directed through the pipe 65, the valve chamber 68 and y 125 the pipe 78 into the chamber 44 in the head 20. A t this time the chamber 41 in the head 19 communica-tes with the tank 63 by means of the pipe 76, the valve chamber 68, and the pipe '73 so that the low pressure iiuid in the 130 chamber 44 will move the plungers 47 and 46 and the piston valve 17 of the control valve to the'left to the Figure 1 position to start apressing stroke of the platen. When the iston valve is moved to the left from the igure 2 position to the Figure 3 position, the discharge from the pump E will be directed through the pipe line 65, the valve chamber 68, and the pipe line 76, and thence into the pressure chamber 41 of the control valve C, and the pressure chamber 44 will communicate with the tank 63 through the medium of the pipe 78, the valve chamber 68,

thebranch 75, and the pipe 73, thus effecting a movement of the iston valve 21 of the control valve to the right to its Figure 3 position for completing apressing stroke of the platen. p

Means responsive to the building up of the pressure in the pressing cylinder 5 when the platen has completed a pressing stroke is provided for moving the piston valve 70 to the left from the Figure 2 position to the Figure 3 position. This means includes a pressure chamber formed in the right hand end of the valve casing 67 of the valve F, and separated from the valve chamber 68 by a partition 8l, and a plunger 82 which eX- tends through an opening 83 in the partition for engagement with the valve 70 and also int-o the pressure chamber 80, where the plunger is formed with a stem 84 which is of reduced diameter and which extends through and projects beyond an opening 85 in the end ofthe valve casing. The reduced diameter 0f the stem 84 provides a resultant shoulder 86 which is acted upon by f'luid under pres-A sure in the `chamber 80.

vThe stem 84 and the plunger. 82 are constantly urged to the right as viewed in the drawings by means of a coiled spring 87 interposed between the valve casing and a hand Wheel 88 threadably mounted on the outer end of the stem 84. A flange 89 on the plunger 84 is adapted to engage the partition 81 and'to thereby limit the movement of the plunger to the right. The chamber 80 is in constant communication with the pressing cylinder 5 through the medium of a pipe 90 which communicates at one of its ends with the chamber and at its other end with an opening 91 in the cylinder 5. Vhen the piston valve 70 is in the position shown in Figure 2 and the platen encounters resistance to its pressing stroke, pressure will build up in the cylinder 5, and this increased or built up pressure will be transmitted to the pres-` sure chamber 80 and will force the plunger 82 to the left. The plunger will then engage Vthe piston valve 70 and move the latter to the left from the Figure 2 position tothe Figure 3 position which will effect a movement of the piston valve 21 from its Figure 2 posi tion to its Figure 3 position to thereby cause the platen to perform a return stroke. It

be engaged by platen-actuated means when the -platen approaches the end of its return stroke. The yplaten actuated means for moving the valve to the right includes an operating rod 95 mounted for vertical sliding movements in lugs 96 and 97 on the press head and the press base respectively, and a collar 98 on the rod which is adapted to engage the lug 97 for limiting the downward movement of the operating rod'. The operating rod is urged downwardly by means of a spring 99 interposed between the lug 96 and a collar 100 on the rod. A boss 101 on the platen is provided with an opening which receives the rod for sliding movements. The boss is adapted to engage a nut 102 adjustably mounted on the rod to lift the rod when the platen approaches the limit of its return stroke. When the rod is lifted by the platen, a cam block 103 on the upper end of the rod engages the roller 94 and moves the latter, to gether with the stem 92 and the piston valve 70, to the right from the Figure 3 position to the Figure 1 position. y L

It will be observed from the foregoing that when the nut 102 is so positioned on the rod 95 as to be engaged by the boss 101 on the platen when the latter approaches the 'end of a return stroke, the'piston valve 70 will be moved to the right from the Figure 3 position to the Figure 2 position and that this will effect the movement of the piston valve 21 of the control valve C to the leftto the Figure 1 position to effect a reversal of travel of the platen and the start of another pressing stroke. Y A When it is desired that the press be operated semi-automatically so that the platen will come to rest at the end of each return stroke, the nut 102 is moved up and set on the rod-95 so as to not be engaged by the boss 101 when the platen moves upwardly, and other means are provided for bringing the platen' to rest at the end of each return stroke. `When the platen is at rest and it is desired to initiate another pressing stroke it isnece'ssary that the piston valve 70 be moved from its Figure 3 position to its Figure 1 position. For accomplishing this movement of 4the valve I provide manually operable means for lifting the operating rod 95. This lifting means comprises a manually operable bell crank lever 104 pivoted to the base 1 as at 105 and having an arm 106 provided with a.

rounded head 107 adapted to engage a collar 108 on the operating rod flor moving the rod upwardly when the bell crank lever is swung in a counterclockwise direction. When the operating rod is thus lifted under manual control the piston valve will be moved to the right from the Figure 3 position to the Figure 1 position and will eiect a shitting of the iston valve 21 of the control valve C to the eft from the Figure 4 position to the Figure 1 position which will start the platenV downwardly on a pressing stroke. v

From the foregoing it will be noted that the pilot valve F 'controls this movement of the piston valve 21 of the control valve which elect reversals ofthe direction of travel of the platen. Y.

It is desirable tnat means be provided for interrupting a stroke of the platen at any time, regardless of the position -of the platen,

'and to this end I have provided manually o erable means for shifting the piston valve 0 of the pilot valve independently of the automatic or semi-automatic operation of the valve. This means includes a manually operable lever 109 pivotally mounted on the press head 2 as at 110 and a lever 111 which is pivoted to the press head as at 112 and which as one arm 113 connected to one arm 114 of the lever by a link 115. The'other arm 116 of the lever 111 is provided with a fork 117 which coo rates with a,l pin 118 on the stem 92 for shi ing the valve when the lever 109 is rocked. When the valves are in the position shown in Figure 1.the platen will perform'a pressing stroke. If it is desired to reverse the platen before it reaches the end of its pressing stroke the manually operable lever 109"wil1 be rocked in aclockwise direction which will move the piston valve 70 to the left toits Figure 3 position -thus eecting a of the piston valve 21 of the control valve C and a resultant reversal of the direction of travel of the platen. jIf it is desired to reverse the platen when the latter is moving on a return stroke thelever 109 will be rocked in acounter-clockwise direction thus moving',vl the piston valve 70 to the right from the Figure 3 position to its Fi ure 1 position v which will in turn eect a s ifting of the iston valve 21 of tbe control valve C toits i igurel position and will produce a reversal of the direction oftravel of the platen.

f "hereinbefore stated, `the first of4 each pressing .stroke ofthe platen4 ieper--` formed when the valves are in the.b Figurefl inwhich position the main pressing 'cylinder 5 is in relatively open communicatlonwith `the so that the descent opfztheiplatenLsduNe to its own weight by in the sur e tank. The low pressure circuit is provide' with means responsiver to the; movement of thek platen, but

operable independently of the particular posifor moving the control valve t0 direct high pressure fluid to the pressing cylinder. This means includes a branch pipe 119 connectedto thek pipe 78, an auxiliary valve G connected to said branch and responsive to the pressure in the low 'pressure circuit, and a pipe line 120 connectedv to the valve G and having constant communication with the pressure chamber 43 in the head 20. The valve G comprises a .valve casing121 formed with a valve chamber 122, a piston valve 123 having spaced heads 124 and 125 mounted in the casing for sliding movements, an o ning 126 in one end of the casing which a ords communication between the branch pipe 119 and the valve chamber, and awsprin 127 interposed between the head and t e other end of the casing forl urging the valve to the left as viewed in the drawings. The branch pipe 119 is arranged 4to ponstantly communicate with the low pressure ends 9 of the platen re-` turning cylinders throughthe medium of a branch pipe 128. The valve casing 121 is provided with a port 129 adapted to afford communication between the valve chamber and the pi 120, and is also provided with a port 130 w ich is adapted to afford communication between the valvelchamber and a branch pipe 131 which is arranged to constantly oom- 4municate with the low pressure return line 73. The ports 129 and' 130' are so located as to be disposed between the heads of the piston valve 123 when the latter is in the Figure 1 position so that normally the chamber 43 of the head 20 communicates with the tank 63 by means of the pipe 120, the valve chamber 122, the pipe r131 and the return pipe 7 3- e When the platen is performing the first a'rt of a pressing stroke the discharge of the lbw ressure pump E will be directed through the ischarge line 65, the valve chamber 68 of the pilot valve F, the pipe line 78, the pipe line 128,; andthence into the low pressure 'ends 9 of the platen return cylinders. The low pressure end o f each platen returning c linder comprises the cylinder volume inc uded between the piston 10 and the upper y"and of the cylinder and it willbe noted that whentheplaten is descending this volume is constantly increasing. The rate of discharge of the low pressure pump is so regulated as to be substantially ual to the rate of increase 'of the volume of t e low pressure ends piti: il 0 platen returning cylinders o'tli'a't' fPltn is descending pressure will not build.

pressure will build-up in the discharge line 65 and the pipe line 7 8.` When the'preure is built upto a value dependent upon the constant of the 127 lathe valve G, the lluid la.l

e rateof discharge. of the pump E, and

pressure acting upon the head 124 of the piston valve 123 will move the latter to the right against the force of the spring until the valve is in the Figure 2 position. When the valve is in this position low pressure fluid will paSs from the branch pipe 119 to the pressure chamber `43 in the head 20 through the medium .of the opening 126 in the valve G, the valve chamber 122, the port 129, the pipe 120 andthe opening 50 in the-head 20. The fluid under pressure thus admitted to the chamber 43 will move the plunger 46 to the left and the plunger will move the piston valve 21 to the left to its Figure 2 position at which time fluid .under pressure from the high pressure pump will be directed to the main cylinder to complete the pressing stroke of the platen. From the foregoing it will be observed that the piston valve 123 is responsive to a change in the rate of movement of the platen for shifting the control valve to apply high pressure iuid to the pressing cylinder.

When the press is arranged for semi-automatic operation the piston Valve 21 of the control valve will be in its Figure 4 position when the platen reaches the limit of its return stroke as has been hereinbefore described. In order to arrest the movement of the platen at the end of its return stroke and to maintain the platen at rest in this position I have provided means for shifting the piston valve 54 of the by-pass valve D to the left from its Figure 1 position to its Figure 4 position. This means comprises a platen actuated pilot valve H connected in the low press-ure circuit for controlling the application of low pressure fluid to the valve chamber of the by-pass valve at opposite ends of the piston valve 54 thereof. The pilot valve H comprises a valve casing 132 formed with a valve chamber 133, a piston valve 134 mounted for sliding movements in the casing 132 and having spaced heads 135 and 136, and a stem 137 connected to the piston valve and projecting through an opening "138 in one end of the casing. An enlarged portion 139 on the stem intermediate the head 136 and the adjacent end of the casing, serves to limit the movement of the piston valve to the right as viewed in the drawings and a spring 140 interposed'between the valve and the opposite end of the casing constantly urges the valve to the right, that is to the position shown in Figure 1.

The valve chamber 133 is at all times i1 communication at its central portion with the pipe line by means of a branch pipe 141 which is connected to the casing at a point intermediate the heads 135 and 136 of the piston valve.' The opposite ends of the valve chamber, that is those portions of the chamber lying between the ends of the casing and the heads 135 and 136 respectively, are in constant communication the return pipe line 7 3 by means of bragi'ches 142 and 143 therein. VThe valve casing132 is pro.-

vided with a port 144 which is so located as to be disposed between the valve heads when the piston valve is in the Figure 1 position,

and with a port 145 which is so located as to be disposed between the valve heads when thc piston valve is in its Figure 4 position. The port 144 is adapted to afford communication between the valve chamber 133 and the left hand end of the valve chamber 53 of the by-pass valve D ,through the medium of a pipe 146 and the opening 61 in the valve casing 52, whereas, the port 145 is adapted to ailord communication between. the valve chamber 133 and` the right hand end of the valve chamber of the by-pass valve D through the medium of a pipe 147 and the opening 62 in the valve casing 52. When the piston valve 134 of the valve H is in its Figure 1 position low pressure iiuid will be directed from the pipe 65 through the pipe 141, the valve chamber 133 and the pipe 146 to the left hand end of the by-pass valve D, thus maintaining the piston valve 54 in the position shown in Figure 1. When the piston valve 134 of the valve H is moved to the left, in a manner to be hereinafter described, low pressure uid from the pipe 65 will be directed through the pipe 141, the valve chamber 133 and the pipe 147 to the right hand end of the by-pass valve D, and will then move the piston valve 54 to the left to itsl Figure 4 position at which time high 4pressure pump fluid will be by-passed to the surge tank and iuid will be trapped in the high pressure end of each of the platen returning'cylinders and will thereby maintain the platen at rest in its uppermost position.

For moving the piston valve 134 to the left when the platen approaches the limit of a return stroke, I have provided an operating rod 148 slidably mounted in lugs 149 and 150 on the press head and press base respectively, a collar 151 on the rod, which isadapted to engage the lug 150 for limiting the downward movement of the rod, and

a spring 152 interposed between acollar 153` on the rod and the lug 149 for urging the rod downwardly. See Figures 1 and 5. A boss 154 on the platen is provided with an opening through which the operating rod passes and which provides free sliding move'- ment between the rod and the platen. A nut 155 threadably and adjustably mounted on the operating rod is adapted to be engaged, by the boss 154 when the platen approaches the end of` its return stroke, the rod being thereby lifted. When the rod is lifted, a roller 156 on the outer end of the stem 137 of the piston valve 134 is engaged by a cam block 157 on the upper endof the operating rod and the valve is moved to the left from its Figure 1 position to its Figure -1 position.

It is to be understoodhat the nut 155 can be so positioned on the operating rod izo iso

as to not be en aged by the platen when the latterapproac es the end of a return stroke so as to permit full automatic operation of the press. When the nut is thus positioned, the valve 134 will remain in the Figure 1 position at all times, and the reversals of the platen will be effected by movements of the piston valve 70 of the` valve F 'in the 1 manner already described. When it is desired that the press operate under, semiautomatic control thenut I155 can be so ositioned as to produce a movement of the piston valve 134 for bringing the platen to rest at any desired point on its upward travel, that is to say, by adjustably positioning the nut 155 on the operating rod, tlie upper limit of the platens travel may be definitely fixed at any desired point.

Operatie/li` If it is desired that the press operate under full automatic control, the nut 102 will be so in Figure 1. In these positions of the valves the pressing cylinder 5 will have relatively open communication with the surge tank through the medium of the valve member 18 in the valve C and the ports 28. At the same time the high pressure end 8 of each of the push back cylinders will have relatively restricted communication with the surge tank by means of the pipe line 34, the valve cham-...

ber 18 in the control valve, and the small opening 29. The ram 6 and the platen 4 willthen coast downwardly under the influence of their own weight assisted by the static pressure of the fluid in the surge tank. 'At this time the discharge from the high pressure pump B will be directed to the surge tank by means of the pipe line .14, the port 33 in the control valve, the paages 37 and 36 in the piston [valve 21, the valve chamber 18, and the port platen the discharge from the low pressure pump E will be' directed through the pipe line 65, the valve chamber 68 in the pilotvalve F, the pipe line 78, the pipe 128, and thence into the low pressure end 9 ofeach of the push yback cylinders, and the net volume of the low ressure ends of the push back cylinders will increaseat a rate substantially equal to or a little greater than vthe rate of discharge of the pump so that ngpressure will build ton valve 21 of the control valve'to the During this gravitational descentof the up in the low pressure circuit and the valves therein will remain in the Figure 1 position.

When the platen encounters resistance to its gravitational' descent and its advance is thereby checked, the net volume of the low pressure ends of the platen returning .cylinders will cease to increase at a rate equal to the discharge of the pump and pressure will'inimediately build up in the pipe lines 6'5 and 78. When the pressure is built up to a predeter'l mined point, fluid under pressure in the branch pipe 119 will act u on the piston valve 123 of the valve G an will move the piston valve to thev right until the' head V124 is .positioned to the right of the port 129 in the valve at which time low pressure iiuid from the branch pipe '119 will be. admitted to the pressure chamber 43 in the head 2O of the control valve C through the medium of the valve chamber 122 of the-valve G, and

the pipe 120. The pressure in the chamber 43 will then move the plunger 46and the e from their Figure 1I positions to their Figure 2 positions. The head 24 of the piston valve 21 will then shut ofthe communication between the ressing cylinder and the surge tank and high ressure iluid from the pumpl B will be admitted to the pressing cylinder through the pipe line 14 an the valve chamber 18 of the control valve, and the high pressureiluid will move the ram 6 downwardly to complete the pressing stroke of the platen.

While the ram is being moved downwardl under high pressure, the hi h'pressure en s of the platen returning cy 'riders will still communicate withthe surge tank through the medium vof the pipe 34, the valve' chamber 18 of the control valve, and the opening 29. After the piston valve 21 ofthe control valve 80 in the valve F by means ofthe opening 91- in the cylinder and the pipe 90. Fludlpres'- 82 will ymove the latter 5 theforce of thespring v87 and the piston pressure will be communicated.""""'v sure acting upon lthe shoulder 86 of ,lim

to the left against valvev 70 will thereby be movedfrom itslig-4 I ure 2 position to its Figure 8 When the piston valve 70 low pressure vfluid will be directed thelow' pressure pump E 'to the pressure'chamber 41 in the head' 19, through the medium of the pipe line 65, the valve lchamber 68' in the valve F, and the pipe 6. 'At the Vsai'iietiine `106 has been moved to its Figure 2 position, there the chamber 43 in the head 20 will communicate with the tank 63 by means of the pipe 120, the valve chamber 122 in the valve G,

the pipe 131 and the pipe 73; and the pres-A sure chamber 44 in the head 20 will communicate with the tank 63 through the mediumv of the pipe 78, the valve chamber 68 in the valve F, the branch 75 of the return line 73, and the return line 73. The fluid under pressure in the chamber 41 will then actupon the plunger 39 to move the latter to the right which willalso move the piston valve 21 of ythe control valve to the right from its Figure 2 position to its Figure 3 position. The pressing cylinder will lnow communicate with the surge tank by means of the valve chamber 18 and the ports 28, whereas the high pressure end of each of the push back cylinders will communicate with the high pressure pump B through the medium of the pipe line 14, the valve chamber 18 and the pipe line 34; and the platen will then perform a return stroke.

When the platen approaches the end of its return stroke the boss 101 Will engage the nut 102 on the rod 95 and will lift the latter, whereupon the cam block 103 will engage the roller 94 and will move the stem 92 and the piston valve 70 to the right from its Figure 3 position to the Figure 1 position. Low pressure fluid from the pump E will now be directed to the pressure chamber44 in the head of the control valve C through the medium of the pipe line 65, the valve chamber 18 in the valve F, and the pipe 78. The lluid under pressure in the chamber 44 will then move the plunger 47 to the left, thus moving the piston valve 21 to the vleft from its Figure 3 position to its Figure 1 position.y The valves kwill then be in the same position that they occupied at the start of the pressing stroke' as described above, and the platen will start another pressing stroke under the influence of its own weight assisted by the static pressure of the fluid in the surge tank.

It will be apparent that when the operating mechanism is adjusted inthe manner described, the press will automatically perform an indeterminate number of pressing operations and that the maximum pressure applied to the work will be uniform and not dependent upon any means whose operation is governed by the position of the platen.

If itis desired to operate the press semiautomatically, or in other words, in such a way that the platen will perform one complete pressing operation and then return to its uppermost position and stop, the nut 102 on the operating rod 95 is moved to a posi'- tion in which it will not be engaged by the boss 101 when the platen moves upwardly, and the nut 155 is moved downwardly on the operating `rod 148 to a position in which it will be engaged by the boss 154 when the platen approaches the limit of its upward travel.

Assuming that the platen is on its downward stroke the completion of this stroke and -v 1.

the start ofthe return stroke will be executed in the same manner as that described in Connection with the full automatic operation of the press.4 lVhen the platen approaches the limit of its returnl stroke the boss 154 will engage the nut 155 and lift the operating rod 148, whereupon the cani block 157 will engage the roller 156 and move the piston valve 134 of the valve H to the left from its Figure 1 position to its Figure 4 position. It will be noted that at this time no movement of the piston valve 70 of the valve F has taken place. Low pressure fluid will now be directed from the pump E to the right hand end of the valve chamber 53 of the by-pass valve D by means of the pipe 65, the branch pipe 141, valve chamber 143 in the valve H and the pipe line 147. At the same time the left handend of the valve chamber of the by-pass valve D will communicate with the tank 63 by means of the pipe line 146, the valve chamber 133 of the valve H, the branch 143 of the return line 73, and the return line 73. Fluid under pressure to the right of the head 56 of the piston valve 54 in the valve D will then move the piston valve to the left from its Figure 1 position to its Figure 4 position. In this position of the valve 54, the discharge from the high pressure pump B will be by-passed to the surge tank by means of the pipe 15, the

valve chamber 53 of the valve D, and the port of said valve. At the same time the head 56 of the piston valve 54 will cover the port 59 and will thus shut oli' communication between the control valve and the valve chamber 53 of the valve D. Because of the factthat in this semi-automatic operation of the press the' control rod 95 was not lifted when the platen approached the end of its return stroke, the pistonvalve of the valve F and the piston valve 21 of the valve C remained .y 1n thelr Figure 3 position lwhen the platen reached the end of its return stroke. Fluid will now be trapped in the high pressure end 8 of each of the platen returnin cylinders and the pipe line 34 by means o the heads 22 and 23 of the piston valve 21 and by the head 56 of the valve 54 which now covers the port l59. This entrapped Huid in the platen returning cylinders will Yprevent the platen from coasting downwardly and will maintain the latter in its uppermost position.

'another stroke.

To cause the platen to perform another complete reciprocation, the bell crank lever 104 is rocked in a counterclockwise direction. This will raise the rod 95 and move the piston valve 70 tothe right froml its Figure 4 position to its Figure 1 position. .This will in turn admit low pressure fluid to the pressure chamber 44 for moving the iston valve 21 of the control valve to the le t from its Figure 4 position to its Figure 1 position and the platen will then start downwardly upon another pressing stroke.

It is to be understood that the manually controlled meansfor moving the piston valve 70 of the valve F, that is the operating lever 109 and associated mechanism, is operable for interrupting the movement of the platen while the latter is performin either a pressing or a return stroke regar less of whether the press is arranged for full automatic operation or for semi-automatic operation. The lever 109 thus provides means for interrupting the movement of the platen in case of emergencies and also for controlling the reciprocations of the platen when it is desired that each stroke thereof be under the control of the operator. v

It is to be understood that the construction and arrangement of parts shown in the drawings is illustrative rather than definitive. As will be obvious .to those skilled in the art, other fluid pressure mediums, such as compressed air, steam or the like could be employed instead of a liquid medium for operating the control valve C. Although I have illustrated a press provided with a platen especially adapted for performing compress.- ing operations, it is to be understood that the invention kdescribed herein may be embodied in presses used for punching, forging, shearin@r or other like purposes and that the term platen is intended to cover any tool, die

y or other appliance with which a press embodying my invention might be provided.

Other modifications in construction and arrangement of parts may be also made without departing from the scope of my invention which is defined in the claims.

I claim as my invention:

1. The combination with a hydraulic press including a reciprocatory platen, a4 pressing cylinder," and a platen returning cylinder;

of a surge tank; a pump means-forming with.l

said pressing cylinder, said platen returning pressing stroke of the platen, and in the third of which positions said valve affords communication between said pump and said platen returning cylinder and also between said tank and said pressing cylinder for effecting a return stroke of the platen.

2. The combination with a hydraulic press -including a reciprocatoryI platen, a pressing cylinder, anda platen returnin cylinder; of a surge tank; a pump; means orming with said pressing cylinder, said platen returning cylinder, said surge tank, and said pump a hydraulic circuit; a valve operatively connected in said circuit for controlling the movements of said platen, said valve eing movable to three positions, in the first of which positions said valve affords communication between said surge tank, said pressing said pump for permitting a gravitational descent of the platen, in the second of which positions said valve affords communication between said ump and said pressing cylinder and also between said platen returning cylinder and said surge tank for completing a pressing stroke of the platen, and in the third of which positions said valve affords communication between said pump and said' platen returning cylinder and also between said tank and said. pressing \,cylinder for effecting a return stroke of the platen; pressure responsive means associated with said valve for moving the latter; and means for applying fiuid'pressure to said pressure responsive means.

3. The combination with a hydraulic press including a reciprocatoryplaten, a pressing cylinder, and a platen returning cylinder; of a surge tank; a pump; means forming with said pressing cylinder, said platen returning cylinder, said surge tank, and said pump a hydraulic-circuit; a valve operatively connected in said circuit for controlling the movements of said platen, said valve in movable to three positions, in the first o which positions said valve affords communication between said surge tank, said pressingcylinder, said platen returning cylinder, and said puin for permitting a gravitational descent o the platen, in the second of which positions said valve affords communication positions said valve aii'ords communicylinder, said platen returning cylinder, and

platen returning cylinder and also between said tank and said pressing cylinder for eecting a return stroke of the platen; pressure responsive means associated with said valve for moving the latter; and means for automatically applying fluid pressure to said pressure responsive means to move said valve to any of said positions.

4. The combination with a hydraulic press including a reciprocatory platen, a pressing cylinder, and a platen returning cylinder; of a surge tank, a pump; means forming with said pressing cylinder, said platen returning cylinder, said surge tank, and said pump a hydraulic circuit; a valve operatively connected in said circuit for controlling the movements of said platen, said valve being movable to three positions, in the first of which positions said valve affords communication between said surge tank, said pressing cylinder, said platen returning cylinder, and said pump for permitting a gravitational descent of the platen, in the second of which positions said valve affords communication between said pump and said pressing cylinder and also between said platen returning cylinder and said surge tank for completing a pressing stroke of the platen, and in the third of-which positions said valve affords communication between said pump and said platen returning cylinder and also between said tank and said pressing cylinder for effecting a return stroke of the platen; means associated with said valve and operable when the platen encounters resistance to its pressing stroke for moving said valve from said first position to said second position; andv means associated withsaidvalve and responsive to the pressure in said circuit for moving said valve fromsaid second position to said third position.

5. The combination with a hydraulic press including-a' reciprocatory platen, a pressing cylinder, and a platen returning cylinder; of a surge tank; a pump; means forming with said pressing cylinder, said platen returning cylinder, said surge tank, and said pump a hydraulic circuit; a valve operatively connected in said circuit for controlling the `movements of said platen, said valve being movable to three positions, in the first of which positions said valve affords communication between said surge tank, said pressing cylinder, said platen returning cylinder, and said pump for permitting a gravitational de- Y scent of the platen, in the second of which positions said valve affords communication between said pump and said pressing cylinder and alsobetween said -platen returnbetween said ing cylinder and said surge'tank for completing a pressing stroke of the platen, and

in the third of which positions said valve affords communication between said pump and said platen returning cylinder and also between said tank and s'aid pressing cylinder for effecting a return stroke of the platen; means associated with said valve and operable when the platen encounters resistance to its pressing stroke for moving said valve from said first position to said second position; means associated with said valve and responsive to the pressure in said circuit for moving said valve from said second position to said third position; and means associated with said valve and responsive to movement of the platen for moving said valve from said third position to said first position.

6. The combination with a hydraulic press including a reciprocatory platen, a pressing cylinder, and a platenl returning cylinder; of a surge tank; a pump; means forming with said pressing cylinder, said platen returning` cylinder, said surge tank, and said pump a hydraulic circuit; a valve operatively connected in said circuit for controlling the vmovements of said platen, said valve being nication between said surge tank, said pressing cylinder, said platen returning cylinder, and said pump for permitting a gravitational descent of the platen, in the second of which positions said valve affords communication ump and said pressing cylinder and also lbetween said platen returning cylinder and said surge tank for completing a pressing stroke of the platen, and in the thirdof which positions said valve affords communication between said pump and :said

platen returning cylinder and also between said tank and said pressing cylinder for effecting a return stroke of the platen; and means operatively connected in said circuit and adapted to place said pump in communication with said tank and to simultaneously trap fluidin said platen returning cylinder when the platen reaches the end of a return stroke.

7. The combination with a hydraulic ress including a reciprocatory platen and hydiaulic platen actuating means for reciprocating the platen; of a surge tank; a high pressure pump; means forming with said platen actuatingmeans, said surge tank, and said pump a high pressure hydraulic circuit; a single valve operatively connected in said circuit or controlling the movements of said platen, said valve controlling communication etween said tank and said platen actuating means and also between said pump and said platen actuating means; pressure responsive valve actuating means associated with said control valve; a source of low pressure fluid; means connecting said source of low presv said pilot va pressure fiuid to said valve actuating means.

sure fluid to said valve actuating means; and means interposedy in said connecting means for controlling the application of low pressure fluid to said valve actuating means.

8. The combination with a hydraulic press including a reciprocatory platen, a pressing cylinder, and a platen returning cylinder; of a surge tank; a high pressure pump; means forming with said pressing cylinder, said platen returning cylinder, said surge tank, and said pump a high pressure hydrauliccircuit; a control valve operatively connected in said circuit for controlling the vmovements of said laten, said valve being movable to three positions, in the first of which positions said valve affords communication between said surge tank, said ressin cylinder, said platen returning cylin er, an said pump for permitting a `gravitational descent of the platen, in the second of which positions said valve affords communication between said pump and said pressing cylinder vand also between said platen returning cylinder and said surge tank for completing a pressing stroke of the platen, and in the third of which positions said valve affords communication between said pump and said platen returning cylinder and also between said tank and said pressing cylinder for effecting a return stroke of the platen; pressure responsive valve actuating means associated with said control valve; a source of low and variable pressurerfluid; means connecting said source of low pressure fluid to said valve actuating means; a valve interposed in said connecting means and operable upon an increase in pressure of said low pressure fiuid for admitting low pressure fluid to said valve actuating means to move said control valve from said first position to said second position; a pilot valve interposed in said connecting means and responsive to an increase in pressure in said high pressure circuit for admitting said increased low pressure fiuid to said valve actu ating means to move said control valve from said second osition to said third position;

l)ve being adapted to admit low to move said' control valve from said third position to said first position; and means for automatically actuating said pilot valve when the platen approaches the end of a return stroke.

9. The combination with a hydraulic press including a reciprocatory platen, a pressing f cylinder, and a platen returning cylinder having a high pressure end and a low prestween said piston and said platen; valve means in said circuit for controlling the admission of high pressure Huid to said pressing cylinder and to the high pressure end of said platen returning cylinder; valve actuating means associated with said valve means; a low pressure pump; hydraulic connections between said low pressure pump, said valve actuating means, and the low pressure end of said platen returning cylinder; means in said flow pressure circuit for directing the discharge of said low pressure pump to the low pressure end of said platen returning cylinder during the initial part of a pressing stroke ofthe platen; and pressure responsive means in said low pressure circuit and associated with said valve actuating means and operable when the platen encounters resistance to its pressing stroke for moving said control valve to effect communication between said high pressure pump and said pressing cylin er.

l0. The combination with a hydraulic press includin a reciprocatory platen, a pressing cylin er, and a platen returning cylinder having a high pressure end and a low pressure end; of a high pressure pump; means forming with the pressing cylinder,

the high pressure end of the platen returning cylinder, and the pump, a high pressure hy draulic'circuit; a reciprocable piston in said platen returning cylinder; a connection between said piston and said platen; valve means in said circuit for controlling the admission of high pressure fluid to said pressing cylinder and to the high pressure end 'of 'said platen returningv c linder; `valve actuating means associate with said valve means; a low pressure pump; hydraulic connections between said low pressure pump, said valve actuating means, and the low pressure end of said platen returning cylinder;

.-means in said low pressure circuit for directing the discharge of said low pressure lpump to the low`pressure end of said platen returning cylinder during the initial part of a pressing stroke of the platen; and pressure responsive means in said low pressure circuit and associated with said valve actuating means and operable when the platen encounters resistance to its pressing stroke for moving said control valve to effect communication between said high pressure pump and said pressing cylinder, the rate of discharge of said low pressure pump being substantially equal to the rate of increase of volume of the low pressure end of said platen returning cylinder during the initial part of each pressing stroke of the platen.

11. The combination vwith a hydraulic press including a reciprocatory platen and hydraulic platen actuating means for reciprocating the platen; of a surge tank; a pump; means forming with the platen actuating means, surge tank, and pump a. hydraulic circuit; a valve in said circuit having a single movable element which is operable to alone control communication between said tank and vsaid platen actuating means, and also between said pump and said platen actuating means; means operatively connected to said valve vfor automatically operating said element to ellect a complete reciprocation of said platen; and manually controlled means for moving said movable element to interrupt the movement of said platen during a pressing stroke irrespective of the position thereof.

In testimony whereof, I have hereunto subscribed my name.

HOWARD F. MACMILLIN. 

